Voltage supply circuits



oct. 17, 1944. R'. B, LlNCOLN 2,360,694

VOLTAGE SUPPLY C IRCUIT Filed Sept. 9. 1942 BY TTO Patented Oct. 17,1944 UNITED STATE s PATENT OFFICE VOLTAGE SUPPLY CIRCUITS Y' RoyLincoln, deceased, late of Newark, N. J.,

by Hazel Lincoln Lang, administratrix, New York, N. Y., assignor toRadio Corporation of America, a corporation of DelawareApplication,September 9, 1942, Serial No. 457,711

` s claims. (c1. 25o-17) An object of this invention is to provide an`The ordinary series screen resistoras usedinv the prior art its notpracticable for a screen grid tube used as a class .C radio frequencyamplier, the excitation ,of which is modulated by being keyed, for thereason that when the space current in the vtube is reduced toa lowvalue. under key-up conditions by the normally cuto fixed bias, thescreen voltage will `rise considerably. This', in turn, necessitates a ve'ry highV value of iixed bias to -keep the anode current anddissipation within reasonable limits.` v

By this invention, the driver tube can.l obtain its anode voltage fromthe same series resistor that supplies the screen of the final tube, andthus reduces the xed bias necessary to obtain the proper anode currentlcut-off in the amplifier.

The invention will best be understood by referring to the accompanying'Adrawing, in which a circuit diagram of the invention is shown.

The keyed oscillation stage I, which maybe any suitable form' ofoscillation generator for developing thedesiredoscillations, isconnected to an electron discharge Vdevice 2, which is preferably of thepentode type, such as the'RCA #47. Device 2 is VVprovided with a grid3,Y anode' 4, screen grid 5, suppressor grid 6 and cathode 1. The device2 serves as the driver stage of a second electron discharge device 8,which acts` as a radio frequency amplifier stage andis preferably of theRCA #813 type of transmitting beam power amplilier. K j

The electron discharge device 8 includes input grid 9, screen grid I0,anode I I, beam-forming electrodes I2 and I3, and cathode I4, ResistanceI6,`connected between ground and grid 3, forms a direct current returnpath for grid 3.

The key circuit includes a key I5, which is coupled to grid 3 by acondenser I1. A coupling condenser IB is connected in series between'anode Ilv and the yinput grid 9 of the radio frequency stage. A tunedcircuit, including inductance I9 and variable condenser 20, is connectedfrom anode 4 to the source of high voltage 2|. A grid bias resistor 22is connected from grid 9 to a source of grid bias voltage indicated as-'-C.'

A second tuned circuit, including inductance 23 and variable condenser24, is connected to anode II of the radio frequency stage, and to thehighl voltage source 2I.` A series resistor 25 is iprovided iorsupplying the proper voltage on screen I0 and is so adjusted that thenormal operating anode and screen voltages appear on the` buffer 2 andthe Iinal tube 8 under key-down conditions.

Y Inl the operation of the circuit of this invention when the key I5 isup, or open, the anode resistance ofthe electron discharge device 2drops to a low value, since its bias Voltage is zero. Because ofresistance 25 the anode voltage of tube 2 and the screen voltage of tube8 drops to a lowvalue. This circuit arrangement saves an additionalpower supply for the anode of tube 2, the screen IIJ of tube 8, the biassupply for grid 3 Vof tube 2, and enables a relatively low value I nectto ground 30 and are provided with condensers 3l and 32. In brief, it isto be noted that tube 2 is provided with a resistor I6 connected betweenthe grid 3 and cathode l. Consequently, in the absence of oscillationsfrom source I, tube 2 draws current, and in the presence of in-put fromsource I, the plate grid of tube 2 is reduced. On'the other hand, theplate current flow through tube 8 is just the reverse for the reasonthat this tube is substantially cut-oil by the -C voltage impressedthrough resistor 22 on the grid 9. `When keyed oscillations reach thegrid 9 of tube 8, plate current ow through tube 8 increases. Hence, itshould be apparent that during periods'of"n`o.signa the current flowthrough tube 2 produces a'voltage drop in resistor 25, which serves tocutdown the'screen voltage on screengrid I0.l f; 1 Y

This invention should not be -limited`to the precise circuitapplication-shown, as it isto'be distinctly understood'that itis capableof being used in other circuit applications where similar circuitcharacteristics exist.

What is claimed is:

l. In combination, a source of modulated high frequency voltage, a firsttube having an anode, a cathode, a grid and a screen grid, a second tubehaving an anode,.a cathode, a grid anda screen grid, a coupling betweensaid modulated high frequency voltage and the grid cathode circuit' ofsaid first tube, circuits coupling the anode and cathode of the firsttube to the grid and cathode of the second tube, a resistanceconnectedacross the grid and cathode of the first tube serving to permitflow of current through saidfirst" tube in the absence of excitationfrom said source ofvr said modulated high frequency voltage, a source ofpotential for maintaining the grid of the second tube negative withrespect to the cathodeof the second tube, a source of anode potentialfor said tubes, and a resistor connected to said source of anodepotential'and-to the screen grids of both of said tubes. f

2. In combination, a source of keyed high frequency voltage, a firsttube having. an anode, a.

cathode, a grid and a screen grid, a second tube having an anode, acathode, a grid and a screen.

grid, a coupling between said source of high frequency voltage and thegrid cathode circuit of said first tube, circuits coupling the anode andcathode of the rst tube to the .grid and cathode of the second tube,aresistance connected across` the grid and cathode of thefirsttubeserving to permit' flow of current throughsaid rst tube in the absenceof excitation from said source of keyed high frequency voltage, a sourceof potential for maintaining the grid of the second grids of both ofsaid tubes, and an input circuit coupled to the grid and cathode of saidfirst tube for applying modulated high frequency voltages thereto.

5. In combination, a source of keyed high frequency oscillation voltagewith a coupling circuit connected thereto, a pair of cascade electrondischarge devices, each havingfanode, grid, cathode and screen gridelectrodes forming a keyed oscillation circuit, and a radio frequencyamplifier circuit respectively, said coupling circuit connectedto'thegrid cathode circuit of the electron discharge device which formsthe keyed oscillation circuit, a source of vvoltage for supplyingvoltage to said'electron discharge devices, a series resistorconnectedto said source of voltage and to the anode vcathode circuit ofat least one of saidl electron discharge devices and forming a part of avoltage divider, and the other electron tube negativevwith respectto thecathode of the second tube, a source of anode. potential for said tubes,and a resistor connected to said source of. anode potential andto the.screen grids of both.,

of said tubes.

3. In combination, a source. of keyedhigh` frequency voltage, a firsttubey having an anode, a cathode, agrid and a screen grid, asecondtube.I

having an anode, a cathode,a grid anda screen grid, a coupling betweensaid source of keyedhigh frequency voltage and the grid'cathode circuitof said first tube, parallel Atuned. circuits coupling, the anode andcathode ofthe first tube tothe.

grid and Ycathode of the second tube, aresistance. connected across thegrid, and cathode of thefirst tube serving to permitA flow `of currentthrough sadrst tube in theabsence of excitation from said sourceofrkeyed high frequency voltage, a source of potential for maintainingthel grid of the second tube negative withrespect toy the cathode ofthesecond tube, a source of anode, potential forsaid tubes, and aresistor connected to said source of anode potential andf.to the,

screen grids of both of said tubes.Y

4. In combination, a first tube having anl anode, a cathode, a grid andascreen grid, a..

second tube having. an anode,a cathode, afgrid and a screen grid,circuits coupling the anode and cathode ofthe first tube to the gridandcathode of the second tube, .ag resistance con.

nected across the grid and cathode of the first.

tube. serving to permit flow of currentIV through said first tube in theabsence, of excitation,` a sourceY of potential for. maintaining. thegrid'of the second tube negative with respect to. the. cathode of thesecond tube, a source of anode potential for said tubes, a resistorconnectedto said source ofanode potentialandto ,the screen dischargedevice forming the other part of said voltage divider'.

6. A' radio transmitting circuit, a source of' high.

frequency voltage,` ay keyed' oscillation circuit coupled to said=sourceof high frequencyvoltageA including an electron discharge device havinganode, grid, cathode and screen grid electrodes, a-grid-leak` biasarrangement for connection to the input gridof said electron dischargedevice, a radio frequency amplifier circuit including an electrondischarge device having a screen grid andinputelectrodes -coupled to theanode'of said' rst'electron discharge device, and having outputelectrodes, asource ofvoltage supply connectedI highfrequency voltage,aV keying circuit for said transmitter coupled to saidi source of highfrequency voltage, said circuit including. an electron discharge devicehaving anode, grid, cathodev and screenv grid electrodes, a grid leakjconnected to the input grid of said electron discharge device,

' a radio frequency amplifier circuit including an electron dischargedevice having anode grid, cathode andscreen ,grid electrodes, a sourceof voltage supply, a resistor connectedin series with said source ofVvoltage supply and the-anode ofiv atleast one ofv said electronrdischarge devices,

the screen grid electrodes of both of the electronl dischargedevicesfbeing connected with the source of voltage supply so. that thefirst mentioned electron discharge ldevice obtains its anode voltagefrom saidresistor, which supplies. the screen grid voltagel to saidradiofrequency amplifierY device having, anode, grid, cathode andscreen.

grid electrodes, a source of voltagesupply, aresistor connected inseries-,with said source of', voltage vsupply and the anode of at leastone, of.

said electron discharge devices, a Variable resistor connected in seriesbetween said screen grid of said second electron discharge device andsaid rst mentioned resistor, the screen grid electrode of the rstmentioned electron discharge device being connected with the source ofvoltage supply and said first mentioned resistor so that it obtainsanode voltage from said first mentioned resistor and the rst mentionedelectron discharge device which serves as part of the Voltage dividerfor said second mentioned electron discharge device.

HAZEL LINCOLN LANG,

Admmstratri of the Estate of Roy B. Lincoln,

Deceased. Y

